Not sure if this should be a bug report or feedback - going with bug report as it appears the wording is simply wrong. The capstone of the new Volcano constellation in Astral Spire reads as follows:
“Enemy players” indicates PvP - is this correct, and the capstone does not apply in PvE battles? That seems unlikely. Other capstones refer to the “Enemy Hero,” which is only relevant in PvP (such as in Jester and Crown), but none refer to “Enemy players” aside from here.
Either Steam Vent does not apply to PvE battles, in which case this bug report can be closed, or Steam Vent does apply to PvE and the wording should probably be tweaked.